Remote Ischaemic Conditioning and Coronary Endothelial Function (RIC-COR)

Intermittent arm cuff inflation reduces the extent of heart muscle injury at the time of cardiovascular injury. The intervention is known as remote ischaemic conditioning (RIC) however the mechanisms by which RIC acts are incompletely understood. One mechanism that might explain the benefits of RIC is an improvement in coronary artery function which in turn might help improve blood flow to heart muscle. The investigators will perform a randomised controlled study of RIC in a minimum of 60 patients with known or suspected angina and in whom coronary angiography with angioplasty would be considered. Following informed consent before the invasive procedure, the patient will be randomly assigned to the intervention group (cuff inflation protocol) or the control group (cuff placement, no inflation; sham protocol). Following initial coronary angiography, endothelial function will be assessed by intra-coronary infusion of acetylcholine in incremental doses. Coronary diameter will be measured after the procedure using quantitative coronary angiography, by a trained observer blinded to the allocated group. Since a neuro-hormonal response may potentially mediate RIC, a blood test will be performed before and after cuff placement in all patients (active and control groups) to measure circulating molecules known to regulate blood vessel function which may be implicated in a RIC-mediated effect on coronary artery tone. This study may provide clinically relevant insights into the mechanisms of action of RIC in patients with coronary heart disease.